PREDICTIONS from a PIECEWISE LINEAR (mixed) MODEL: THEY AIN'T LINEAR BETWEEN BREAK POINTS!!
On 11-03-18 08:42 AM, Federico Bonofiglio wrote:
I Dears, if that wouldn't take u too much effort I'd like to ask for a swift opinion: I have a alinear (mixed effect) model that I wish to run as a piecewise one. When I predict the values Iget quite some odds and disturbing results: The predicted stright line after the break point is not straight at all, instead behaves like if it was a hig order polynomial or something similar!!!! I attach the codes below, hoping someone can point me the mistake.... I sincerely express many thanks in advance ...... Federico Bonofiglio
You have not given us a *reproducible* example ...
I would guess that you need I(rt>15) rather than rt>15 in your formulae.
good luck
Ben Bolker